Clearly, a compressor generates pulses, which in turn generate noise when in operation. Therefore, a number of technical solutions were developed over the years to reduce or even try to eliminate the noise generated. Among said solutions, there is the suction acoustic filter, which can be provided in compressors such as those used in applications for cooling systems of household appliances.
The suction acoustic filter is generally arranged in the compressor between the refrigerant fluid inlet and the valve, so that its inlet receives the refrigerant fluid which has passed through the evaporator and its outlet delivers said fluid to the cylinder, so that it is compressed by the piston.
The acoustic effect of the filter is obtained by the various geometric configurations that said device may have. Thus, according to the geometric configuration chosen or projected, the pulses of the pressures may be attenuated by the effect of passive cancellation.
A common problem for a person skilled in the art is to be able to combine good acoustic performance with good thermodynamic performance. Generally, said two objectives are related inversely proportional, in other words, when a filter has good performance in pulse attenuation, the thermodynamic performance thereof is relatively reduced, and vice versa.
An example that can be obtained from the state of the art is in document U.S. Pat. No. 6,206,135. Said document describes a suction acoustic filter for hermetic compressors endowed with a refrigerant fluid path. From the figures of said document, it is possible to verify that the path has a specific sinuous shape, which connects the refrigerant fluid inlet to the refrigerant fluid outlet. In addition, along said path there are resonance chambers parallel to the flow.
However, although the filter presented by the document U.S. Pat. No. 6,206,135 may achieve the effect of reducing noise, it should be noted that the assembly thereof is complex. Said complexity comes from the fact that said path has an unconventional shape, in other words, it is rather sinuous and narrow in some regions, in addition to the fact that there is more than one resonance chamber. Moreover, the fact that said filter has several inner walls increases the amount of material for its manufacture, which makes this product more expensive. Finally, allied with all said disadvantages, it is important to note that the sinuous and narrow sections have relatively lower thermodynamic performance, as a person skilled in the art must quickly intuit.
As can be observed, in general, it is noted that the state of the art lacks a filter having, simultaneously, a good thermodynamic and acoustic performance.